1. Field of the Invention
The present invention relates to a remote operating system for operating a device from a remote location using an operating terminal, an apparatus for use in the remote operating system, and a remote operating method.
2. Related Background Art
It is currently possible to remotely operate various devices, such as televisions, air conditioners, and video recording apparatuses, using so-called remote controllers based on wireless communication techniques. There is also realized a system in which a camera server is installed on the Internet and camera operations, such as panning, tilting, and zooming, are performed at a remote location using a WWW browser, thereby allowing live videos to be watched at the remote location.
In such a system, an operating terminal remotely operates a remote operation target device installed at a remote location by performing information exchange with the remote operation target device using TCP/IP (Transmission Control Protocol/Internet Protocol) that is a standard communication protocol used on the Internet. In this system, it is possible to remotely operate the remote operation target device via the Internet from all over the world. In particular, if the system adopts a protocol called HTTP (HyperText Transfer Protocol, a protocol higher than TCP/IP) that is a standard protocol used in WWW systems, it is possible to remotely operate the remote operation target device even from an operating terminal existing inside of a local network protected by a firewall so long as it is possible for the operating terminal to browse WWW pages using a WWW browser.
Also, if a WWW proxy server is installed on the firewall, it is possible to connect to a WWW server existing on the Internet and to browse WWW pages using the WWW browser via the WWW proxy server. This is because the WWW proxy server relays HTTP commands issued inside of the network protected by the firewall to the Internet. That is, if the HTTP protocol is adopted as a communication protocol, it is possible to perform communications from the network inside of the firewall to the remote operation target device via the Internet.
However, in the case where the remote operation target device exists inside of a firewall, even if the system adopts the HTTP protocol as a communication protocol, it is impossible for the operating terminal to remotely operate the remote operation target device via the Internet.
This is because a firewall is ordinarily set so that only if a device inside of the firewall issues a stream-oriented connection (TCP connection) request to a device outside of the firewall, the connection request is allowed to pass through the firewall. This means that even if the device outside of the firewall issues a connection request to the device inside of the firewall, this connection request is not allowed to pass through the firewall. In the case of stream-oriented connection, a connection request issued from a device and a response issued from another device receiving the connection request are dealt with as a pair. Therefore, only if the authorized device inside of the firewall issues the connection request to the request receiving device outside of the firewall, the communication from the outside request receiving device to the inside is allowed to pass through the firewall. By regulating accesses from devices outside of a firewall in this manner, there is reduced the danger of receiving attacks from the outside.
Accordingly, in the case of an ordinary setting of a firewall installed to prevent attacks against a network, there was a problem in that although WWW pages can be browsed from the inside of the network, it is impossible to remotely operate a remote operation target device installed inside of the firewall via the Internet even if a remote operating system is constructed using the HTTP protocol.